This fly was photographed on flower heads of Encelia actoni, a member of the Sunflower family (Asteraceae) at ~7000 ft elevation in the Inyo Mountains. (Yes, it was November!)

It keyed clearly to Bombyliidae (in Borror, Triplehorn & Johnson(1), and Cole(2)), and continuing with the keys and descriptions in Cole(2) and Hull(3) led fairly nicely to subfamily Phthiriinae and genus Phthiria. Initially, I was a bit discouraged when I saw that the BugGuide entries for Phthiriinae looked very different from this fly (light-colored for one). But Cole(2) states that in the genus Phthiria ... "males generally differ markedly from the females and are often largely velvety black". (That passage was somewhat reassuring:-) Also, this image from the Harvard MCZ website makes Phthiria seem like a good fit. Hull(3) mentions that these flies are strongly attracted to members of the sunflower family. Cole(2) states that, in 1969, there were likely many undescribed species in the southwest.

If you have comments or ideas here...I'd love to hear them.